Theory Seminar: Dynamical Quantum Phases: New routes to ergodicity breaking in interacting many-body systems

 

Michael Knap
It has been the believe that generic quantum many-body systems necessarily approach thermal equilibrium after a long time evolution.

Michael Knap
Herbert-Walther Lecture Hall G0.25
Wed 8. May 2019, 11:30 am (MEZ)

Abstract:

It has been the believe that generic quantum many-body systems necessarily approach thermal equilibrium after a long time evolution. As a consequence any quantum information encoded in the initial state is lost in the course of the dynamics and the late time dynamics is described by simple hydrodynamics. However, recently exceptions have been found to the rule. For example, disordered and interacting many-body systems realize the non-ergodic, many-body localized phase. In this talk, we show how constraints can significantly alter the quantum dynamics of interacting many-body system. To this end, we will first discuss the far-from-equilibrium dynamics of a two-dimensional quantum dimer model, which leads to a rich dynamical phase diagram with some almost ergodicity breaking regimes [1]. As a second example we show that the combination of charge and dipole conservation, characteristic of fractonic quantum matter, leads to an extensive fragmentation of the Hilbert space, which in turn can lead to a breakdown of thermalization [2].

1.        Dynamical Phase Transitions in the Quantum Dimer Model on a Square Lattice. Johannes Feldmeier, Frank Pollmann, Michael Knap [arXiv:1901.07597]
2.        Ergodicity-breaking arising from Hilbert space fragmentation in dipole-conserving Hamiltonians. Pablo Sala, Tibor Rakovszky, Ruben Verresen, Michael Knap, Frank Pollmann [arXiv:1904.04266]